This invention is concerned with a device for assisting the initial opening of a four-link hinge for a vehicle lid and to a four-link hinge for a vehicle lid fitted with such a spring device, and in particular to such a spring device that may be fitted to an assembled four-link hinge without the need for tools.
Four-link hinges are often used on the boot lids of European cars because they intrude less into the boot space when the lid is closed, and enable the lid to be opened to a greater angle from its closed position than the more conventional hinge comprising a single curved link. Use of such four-link hinges on car boot lids increases the usable boot space and improves access thereto.
Four-link hinges in general comprise a gas strut connected between two of the links and operable to open the hinge by acting upon said two links. However, it has been found that the line of action of the gas strut is such that it acts to open the hinge only once the hinge is partially opened. This means that the boot lid initially seems to be excessively heavy to a person attempting to open it, and prevents the lid from being opened from inside the car using a remote catch, since the boot lid is held closed by its weight and locks again as soon as the remote catch is released.
Several arrangements have been proposed for opening the hinge to the point where the gas strut starts to act, including, in one arrangement a folded leaf spring attached to a first link and acting upon a second link, and in a second arrangement a cam pivotally attached to one of the links such that the gas Strut initially acts upon the cam rather than the link itself to open the hinge.
Car manufacturers have been slow to accept either arrangement for a number of reasons, but principally because of their appearances, and their tendencies to distort the lid when in the closed position.
According to a first aspect of the present invention there is provided a device for assisting the initial opening of a hinge for a vehicle lid, comprising an elongate body in which a plunger is slidable, the plunger being engageable with the hinge, and spring means disposed in the body and acting on the plunger to urge it into an extended position.
Thus the invention provides a device for assisting the initial opening of a hinge for a vehicle boot lid that is discrete in appearance and does not cause the hinge to distort the boot lid when in the closed position.
Preferably the plunger engages with the hinge only when the binge is in a closed position and during the initial opening of the hinge from the closed position.
Preferably the plunger is retained by a fastening means attached to the elongate body.
Preferably the elongate body, plunger and annular fastening are formed from rigid plastics material.
The rigid plastics material may advantageously be an acetal resin.
Preferably the spring means is a helical compression spring.
Advantageously the spring means may be damped such that the plunger moves to the extended position at a controlled rate.
Preferably the elongate body has a cylindrical internal cavity having an opening to accommodate the plunger, the plunger being cylindrical and the fastening means being annular.
Preferably the elongate body is formed with an annular recess at the opening of the cylindrical internal cavity In which radially projecting ribs formed on the annular fastening engage.
According to a particularly advantageous feature of the invention the plunger may be formed such that in the extended position it exerts a radial outward force upon the annular fastening and forces the radially projecting ribs into the annular recess to strengthen the attachment of the annular fastening to the elongate body.
According to a second aspect of the invention there is provided a four-link hinge for a vehicle lid comprising a main spring means or gas strut operable against one of the links to urge the hinge into an open position, and a device for assisting the initial opening of the hinge, wherein the device comprises an elongate body in which a plunger is restrained by an annular fastening attached to the elongate body, and spring means for urging the plunger into an extended position for engagement with the hinge.
Preferably the elongate body comprises a flexible angled member which extends from a wall of the elongate body to define a slot between the flexible angled member and said wall, thereby enabling the device to be mounted upon a first link of the hinge such that when the hinge is closed, the plunger acts upon part of the hinge to assist the initial opening thereof.
Typically the hinge is a hinge of a vehicle boot lid but may be, for example, the hinge of a vehicle bonnet.
Preferably the four-link hinge comprises a body link for attaching to a vehicle body, a lid link for attaching to a vehicle lid, short and long links joining the body and lid links, and a gas strut attached between the body and lid links, said device being attached to the long link such that the plunger acts upon the end of the gas strut attached to the lid link.
The long link may advantageously be cranked or kinked to accommodate the device within the hinge without increasing the overall width of the hinge.
Advantageously the elongate body may further comprise a stud which projects into said slot to engage with an aperture in one of the links, such that said flexible angled member may be sufficiently deformed to enable the stud to pass over the thickness of the link until the stud engages with the aperture, thereby securing the device in position upon the link.